Computed Tomography (CT) Scan of the Head and Face

Test Overview

A computed tomography (CT) scan uses X-rays to make pictures of the head and face.

During the test, you will lie on a table that is attached to the CT scanner, which is a large doughnut-shaped machine. Your head will be positioned inside the scanner. The CT scanner sends X-rays through the head. Each rotation of the scanner provides a picture of a thin slice of the head and face. One part of the scanning machine can tilt to take pictures from different positions. All of the pictures are saved as a group on a computer. They also can be printed.

In some cases, a dye called contrast material may be put in a vein (IV) in your arm or into the spinal canal. The dye makes structures and organs easier to see on the CT pictures. The dye may be used to check blood flow and look for tumors, areas of inflammation, or nerve damage.

A CT scan of the head can give some information about the eyes, facial bones, air-filled cavities (sinuses) within the bones around the nose, and the inner ear. If these areas are of concern, a specific CT scan of the area is usually done.

Why It Is Done

A CT scan of the head is done to:

Find the cause of symptoms, such as confusion, paralysis, numbness, vision problems, vertigo, or headaches, that might mean a brain injury, a brain tumor, a ruptured aneurysm, or bleeding inside the head.

Become very nervous in small spaces. You need to lie still inside the CT scanner, so you may need a medicine (sedative) to help you relax.

Arrange for someone to take you home in case you get a medicine to help you relax (sedative) for the test.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, or how it will be done. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

A CT scan is usually done by a radiology technologist. The pictures are usually read by a radiologist, who writes the report. Other doctors also may review a CT scan.

You may need to take off any jewelry, glasses, and hearing aids. Wear comfortable, loose-fitting clothes.

During the test, you will lie on a table that is attached to the CT scanner. Straps will hold your head still, but your face will not be covered.

The table slides into the round opening of the scanner, and the scanner moves around your body. The table will move while the scanner takes pictures. You may hear a click or buzz as the table and scanner move. It is very important to lie still during the test.

During the test, you may be alone in the scan room. But the technologist will watch you through a window. You will be able to talk to the technologist through a two-way intercom.

The test will take about 30 to 60 minutes. Most of this time is spent getting ready for the scan. The actual scan only takes a few seconds.

How It Feels

The test will not cause pain. The table you lie on may feel hard, and the room may be cool. It may be hard to lie still during the test.

Some people feel nervous inside the CT scanner.

If a medicine to help you relax (sedative) or dye (contrast material) is used, an IV is usually put in your hand or arm. You may feel a quick sting or pinch when the IV is started. The dye may make you feel warm and flushed and give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache. Tell the technologist or your doctor how you are feeling.

Risks

If you have diabetes or take metformin (Glucophage), the dye may cause problems. Your doctor will tell you when to stop taking metformin and when to start taking it again after the test so you will not have problems.

There is a small chance of developing cancer from having some types of CT scans.1 The chance is higher in children, young adults, and people who have many radiation tests. If you are concerned about this risk, talk to your doctor about the amount of radiation this test may give you or your child, and confirm that the test is needed.

The brain and blood vessels and bones of the skull and face are normal in size, shape, and position.

No foreign objects or growths are present.

No bleeding or collections of fluid are present.

Abnormal:

A growth, such as a tumor, or bleeding is present in or around the brain. Foreign objects, such as glass or metal fragments, are present. The bones of the skull or face are broken (fractured) or look abnormal. Nerves leading to or from the brain are damaged or pinched.

A collection of fluid is found, which may mean bleeding in or around the brain.

What To Think About

Children who need a CT scan may need special instructions for the test. If the child is too young to hold still or is afraid, the doctor may give the child a medicine (sedative) to help him or her relax.

If your child is scheduled for a CT scan, talk with your child's doctor about the need for the scan and the risk of radiation exposure to your child.

Special CT scanners called spiral (helical) CT scanners and multi-slice (or multi-detector) CT scanners are sometimes used for this test. They can find aneurysms or atherosclerosis. These special CT scanners can:

Take better pictures of blood vessels and organs.

Produce scans in less time.

Perfusion CT is a method to look at blood flow in the brain. For this test, a dye (contrast material) is given intravenously (IV), and CT scans then follow the flow of the dye through the brain. This type of CT scan can show damaged areas of the brain. The scans also can show areas of the brain that are not getting any blood flow.

CT results are often compared to positron emission tomography (PET) results to help find cancer. Some new scanners do both scans at the same time.

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